This invention relates generally to hydrotherapy and more particularly to improvements in hydrotherapy jet installations for use in water tubs, typically referred to as spas, hot tubs, and jetted bathtubs.
Hydrotherapy jet assemblies of various configurations are well known in the art and are readily commercially available. Such assemblies are typically comprised of a housing adapted for mounting behind an opening in a tub peripheral wall. A nozzle mounted in the housing receives water under pressure from a water supply pipe and discharges a water jet through a mixing chamber, creating a low pressure therein, and drawing ambient air into the chamber, via a suction opening, from an air supply pipe. The water jet entrains the air and the resulting water/air stream then exits through a tubular flow director having a discharge orifice into the tub, below the surface of a water pool therein.
Exemplary prior art jet assemblies are disclosed in U.S. Pats. Nos. 3,890,655, 3,890,656, and 3,949,449. These particular patents were the subject of litigation in Mathis v. Hydro Air Industries, Inc. 1 U.S.P.Q. 2nd 1513 (D.C. C.D. CA, 1986). The case, as reported, includes a listing of additional prior art at pages 1524, 25.
The water/air stream preferably exits from the discharge orifice at a high velocity for the dual purposes of creating turbulence in the water pool and impacting against a user's body. Typically, the tubular flow director, or "eyeball", can be manually adjusted by the user to enable him to selectively direct the discharged stream. Then, by moving his body relative to the stream, the user is able to massage various body muscles.
Parenthetically, it is pointed out that whereas typical jet assemblies enable the user to direct the discharge stream in a selected, but stationary direction, applicants' copending applications Nos. 843,151 filed Mar. 24, 1986, 902,179 filed Aug. 29, 1986, 796,987 filed Nov. 12, 1985, and 038,780 filed Apr. 15, 1987, disclose jet assemblies for discharging a stream while concurrently translating the stream along a path oriented substantially perpendicular to the stream direction.
Hydrotherapy jet assemblies are typically used in situations where it is desired to maintain the water pool at an elevated temperature for the comfort of the user. (In spa and hot tub situations, the water is typically circulated through a heater to maintain the desired water temperature. In bathtub situations, the tub is typically first filled with hot tap water and then additional hot tap water is added as required). It is commonly recognized, however, that the ambient air entrained by the water jet acts to lower the water temperature thus requiring more heater intervention or more hot water replacement. Although it might at first seem that this problem could be readily avoided by reducing the amount of air entrained by the water jet, this solution is not acceptable because the intensity of the discharge stream typically diminishes considerably as the amount of entrained air decreases.
This reduction in discharge stream intensity (i.e. momentum) occurs because the area of the nozzle outlet is typically much smaller than the area of the passage through the flow director to the discharge orifice. The discharge orifice is typically made longer to define a larger impact spot against the user's body. When sufficient air is entrained by the water jet, the air tends to fill the difference in area between the discharge orifice and the nozzle outlet to thus maintain the velocity (and momentum) of the water jet. When the amount of air is reduced, the velocity of the water slows thus diminishing the intensity of the stream exiting from the discharge orifice.